Method for manufacturing crystalline confectionery food products

ABSTRACT

A feed stock comprising sugar, milk solids, a significant amount of moisture, and in some instances chocolate, is raised to a temperature of about 125° C. and at the same time is condensed to have a moisture content of between about 4% and 6%. This is done by moving the material upwardly in an annular column and heating the walls defining that annular column. The condensed material is maintained at its final temperature and transferred to a crystallizer. In the crystallizer it is moved downwardly and kneaded. The kneading is performed by two sets of interdigitating rods, one set being stationary and the other set moving transversely to the downward path of movement of the material. As it is being kneaded it is cooled, both by contact with refrigerated surfaces and also by a countercurrent flow of cool air. The kneading is continued until the product is crystallized and particulate. Thereafter, it is optionally dried to a moisture content of about 1%.

BACKGROUND AND SUMMARY OF THE INVENTION

The present invention is primarily concerned with the crumb process ofmanufacturing milk chocolate, although the concepts involved can beutilized in the manufacture of other products which are to becrystallized from a material which is viscous and sticky and for thecondensing of a feed stock which becomes viscous and sticky when in itscondensed state. The present commercial process of producing milk crumbis described in the book Chocolate, Cocoa and Confectionary: Science andTechnology, Bernard W. Minifie, published by The AVI Publishing Company,Inc. (1970), particularly pages 91-93. To summarize, the milk is firstevaporated at a temperature of 75° C. to about 30-40% solids in acontinuous evaporator. Sugar is added and the milk/sugar mixture iscondensed in pans under vacuum at a temperature of about 75° C. to about90° solids. Chocolate (the term is used herein to include cocoa) liquoris put in heavy mixing equipment, such as a melangeur, and while thatequipment is operating a batch of that condensed milk/sugar is graduallyrun in and kneaded by the equipment. This produces a batch of stiffmagma which is placed in shallow trays and vacuum dried at a temperatureof 75° - 105° C. This generally is a batch operation although someefforts have been made to use a continuous process.

The present invention is a continuous process wherein all of theingredients, including the chocolate (which is optional depending uponthe desired final product), are initially mixed together to form aliquid feed stock. Essentially the feed stock comprises sugar, milksolids and a substantial amount of moisture (e.g., 28-30% by weight).This feed stock is evaporated in a continuous evaporator to produce acondensed mixture having about 4-6% moisture (by weight) and atemperature of about 121.1° C. (250° F.) to about 126.67° C. (260° F.).The material at this stage is viscous, sticky and ready to crystallize.It has the consistency of a paste (e.g., toothpaste). It is thenpromptly kneaded and cooled in a continuous operation during which itcrystallizes in the form of small particles.

The condensation is performed in a vertical evaporator having anannular, narrow process passageway, both walls of which are heated andscraped. Upon reaching the top of that passageway the material ismechanically moved to the crystallizer and care is taken to maintain thematerial temperature at about the same as that when it came from theprocess passageway. The crystallizer also has an annular verticalpassageway through which the material moves in the downward direction.This passageway decreases in cross-sectional area between its uppermostand lowermost portions. One of the annular walls that defines thispassageway rotates with respect to the other. Both walls carry aplurality of mixing elements that project horizontally into thepassageway, with the elements interdigitating in the vertical direction.These perform the kneading operation which is a pulling, stretching andworking of the condensed material.

The method and apparatus of the present invention have numeroussignificant advantages over the present commercial practice. Among theseare: based on an equivalent daily production rate, the cost of theapparatus utilizing the present invention is only a fraction of thatrequired for the conventional batch process. Similarly, the requiredfactory space is greatly reduced by the present invention. The presentinvention does not require that most of the operations be conductedunder a vacuum as do the present commercial processes, although a vacuumcould be used in the evaporator of the present invention if desired. Anincrease in uniformity of resulting crumb is achieved. The process inaccordance with the present invention is more readily adaptable to avariety of conditions than is the case with conventional operations andthus provides substantial flexibility. The operator can readily producedifferent products at different times using the same apparatus.

In the manufacture of milk (or chocolate) crumb an important feature isthe reaction of the sugar and milk solids during evaporation to producecaramelization. This reaction is an important factor in the flavor ofthe resulting product. Various manufacturers have different aims as tothe flavor to be achieved. Through the use of the present process andapparatus, a manufacturer will have little difficulty in consistentlyobtaining just the flavor he desires.

In the manufacture of crumb, it is important to form small size sugarcrystals. Large crystals are undesirable as they cause difficulties insubsequent processing; they are abrasive to equipment; etc. Ifcrystallization is incomplete an amorphous sugar "glass" is formed whichalso causes processing difficulties. In the present invention it ispossible to substantially eliminate glass from the resulting crumb,which is not always the case with conventional operations.

Further objects and advantages will become apparent from the followingdescription.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevational view, partially broken away, of an embodimentof the invention;

FIG. 2 is a section taken at line 2--2 of FIG. 1;

FIG. 3 is an enlarged view of the upper portion of the apparatus as seenin FIG. 1; and

FIG. 4 is a section as viewed at line 4--4 of FIG. 3.

DESCRIPTION OF SPECIFIC EMBODIMENT

The following disclosure is offered for public dissemination in returnfor the grant of a patent. Although it is detailed to ensure adequacyand aid understanding, this is not intended to prejudice that purpose ofa patent which is to cover each new inventive concept therein no matterhow others may latter disguise it by variations in form or additions orfurther improvements.

In the present invention there is a vertical evaporator, generally 10.The liquid feed stock is introduced into the bottom of this evaporatorand by the time it gets to the top it is a hot, thick, concentratedmaterial (4-5% moisture). A transfer means, generally 11, moves thisconcentrated material to a crystallizer, generally 12. In thecrystallizer the material is kneaded (worked, pulled, etc.) and cooled.Upon discharge from the crystallizer it is a crystalline product inparticulate form. If the particulate product is to be stored rather thanto be used in the near future, it is dried down to about 1% moisture ina drier, generally 13. The particular form of drier is not important tothe present invention. For the purposes of illustration it is a tunneldrier with the product being carried therethrough on a conveyor,generally 14.

Evaporator

During evaporation, the material being evaporated flows upwardly throughan annular passage 16 which is defined by inner and outer concentricwalls 17 and 18. This passage is relatively narrow in the radialdirection, e.g., about 15.87 mm (5/8 of an inch). The inner wall has asteam jacket 19 and the outer wall has a steam jacket 20. Steam isintroduced into the chamber defined by the inner steam jacket through apipe 22 having an external connection 22a. The connection for thecondensate return of both jackets is shown at 23. The steam chamberdefined by the external jacket 20 has a steam connection 24.

There is a source of steam as represented at 26. The steam from thatsource is fed to a series of temperature controls as represented at 27.Dot-dash line 28 represents the steam supply to inner jacket connection22a. Dot-dash line 29 represents the steam supply to outer jacketconnection 24. The condensate return for both jackets is represented bydot-dash line 30.

The material passage 16 has a header (not shown) at the bottom thereofwhich communicates with an external connection 32. The feed stockmaterial from a source 33 is fed into this connection 32 under pressureby a pump 34. This pump is a variable speed, positive displacement pump,thereby permiting control of the rate at which the material passesthrough the evaporator.

A vertical shaft 36 is mounted in suitable bearings and is rotated by avariable speed power drive 37. A typical rotational speed would be 80rpm for a 13.02 cm (5.125 inch) diameter rotor, but this would obviouslyvary with the rotor diameter. Rotatably secured to the top of the shaftis a spider 38. A plurality of rods 39 are welded to this spider andalso to a rotor 40 which extends down through material passage 16. Thusthe rotor is supported and rotated by shaft 36. A plurality of scrapers41, only a portion of which are shown, are secured to the rotor toscrape both the inner and outer walls 17 and 18 of the material passage.

The top of the material passage is enclosed by a housing 43. Theinterior of this housing is open to atmosphere through a connection 44.Some operators may desire to operate the evaporator under vacuum inwhich case the connection 44 is employed to connect to the vacuumsource, not shown. The housing includes an annular horizontal wall orshelf 45 which terminates in an annular vertical wall 46. A steam jacket47 is employed to provide a chamber for the heating of wall 45, althoughit does also heat the very top portion of wall 18. Similarly, a steamjacket 48 is employed to heat that part of wall 46 within which thematerial will come into contact. Jacket 47 has supply and condensateconnections 49 and 50. Jacket 48 has supply and condensate connections51 and 52. From temperature control 27 steam is supplied to connections49 and 51, as indicated by dot-dash lines 54 and 55. The return pipingfor the condensate is indicated by dot-dash lines 56 and 57.

Transfer Means

Functionally, the heated walls 45 and 46 are a part of the transfermeans because their function is to maintain the proper temperature ofthe condensed material for the purpose of facilitating its removal fromthe evaporator before crystallization commences. The material isdischarged from the housing through an opening 60 in walls 45 and 46.

A tube 61 communicates with opening 60. A substantial portion of thistube is heated by steam jacket 48. A second tube 62 is concentric withthe first and secured thereto. This second tube has a discharge opening63. A third tube 64 is secured to tube 62 and communicates with opening63. A steam jacket 65 surrounds most of tubes 62 and 64. This jacket hasa steam connection 67 and a condensate connection 68. Connection 67 ispiped to the temperature controls 27, as indicated by dot-dash line 69.The condensate connection is piped to the source of steam, as indicatedby dot-dash line 70.

A plurality of paddles, only one of which is shown in the drawings, areused to move the condensed material from the housing 43 into opening 60.These paddles comprise a mounting member 72 to which a replaceablescraper blade 73 is attached, as by means of bolts 74. This scraperblade scrapes both walls 45 and 46. Mounting member 72 is secured to arod 39, as by means of clips 75. Alternatives such as U-brackets boltedonto the mounting member could be employed. An elongated clip 76 is usedat the bottom to give the proper angular position to the mounting memberand scraper blade. In this respect, it will be noted that the spider 38rotates in the direction indicated by arrow 77. The scraper will thusmove the thick material away from the evaporator passage 16 and crowd itinto opening 60 as the scraper passes that opening. As best seen in FIG.4, tube 61 angles away from the housing in a direction to facilitate theflow of the material through opening 60 and down the tube.

It is desirable to get the condensed material out of the housing 43 aspromptly as possible, not only from the standpoint of preventing furtherevaporation, but also it is ready to immediately start crystallizing andthe operation will be impaired if that occurs substantially before itgets into the crystallizer. To this end, a substantial number ofscrapers are employed. The exact number will vary with conditions. Byusing different rods 39 for the mounting of scrapers, the number andpositioning of the scrapers can be varied as required.

A helical conveyor 80 is rotatably mounted in tubes 61 and 62. The upperend of this conveyor is as close as possible to the scraper blades 73.This conveyor is attached to a gear drive motor 81 and rotated so as todraw the condensed material down the tube to opening 63. From opening 63the material flows down to the bottom of tube 64 and then descends bygravity to the crystallizer. This will occur both by reason of the pull12.78°gravity on the material in tube 64 and also by the pressure thatthe helical conveyor 80 applies to the material in tube 62 which in turnapplies pressure to the material in tube 64. The operation of thehelical conveyor is better if it is coated with a slippery material suchas Teflon.

Crystallizer

The crystallizer 12 comprises a stator 85 within which is a rotor 86.The stator comprises an annular wall made up of an upper solid part 87and a lower wall part 88 having a jacket 89 thereabout. The jacketdefines an annular coolant chamber having an input connection 91 and adischarge connection 92. As indicated by dot-dash lines 93 and 94,coolant is circulated through this chamber from a source of liquidcoolant 95. This source could be tap water (e.g., 12.78° C.).

The rotor comprises a shaft 97 rotatably mounted in top and bottombearings 98. Sprockets 99 are secured to the shaft and chains 100connect these sprockets to a variable speed power drive 101 to rotatethe shaft. The rotor has an outer wall which, in the illustratedembodiment, is formed by three sections, namely, a lower cylindricalsection 103, a truncated conical middle section 104 and an uppercylindrical section 105. There is a coolant jacket 106 about the insideof the lower wall 103 to define a chamber for receiving the liquidrefrigerant. A pipe 107 communicates between the upper part of thischamber and the interior of shaft 97. The shaft is divided by a wall109. A pipe 110 extends through this wall and to a rotary joint orstuffing box 111 at the bottom of the shaft. There the pipe 110communicates with a discharge connection 112 on the rotary joint. A pipe113 communicates with the lower end of the coolant chamber and theinterior of shaft 97 below wall 109. At the lower end of shaft 97, thatpart of the shaft surrounding pipe 110 communicates through the stuffingbox 111 with an intake connection 114 on the stuffing box. As isindicated by dot-dash lines 115 and 116, the connections 112 and 114 onthe stuffing box are connected to the refrigerant source 95. Thus thecoolant enters the coolant chamber through pipe 113 and exits from thechamber through pipe 107.

The space between the rotor and stator forms an annular product passage118. This passage is larger at the top than at the bottom. While in theillustrated embodiment, the change in area of the passage is defined bythe truncated conical wall 104, other configurations could be employed,as for example: the rotor could be of truncated conical configurationthroughout its total height; the rotor could be cylindrical and thestator could be an inverted truncated conical configuration; etc.Extending from the rotor into the material passage 118 are a pluralityof rods 119. A plurality of rods 120 extend from the stator wall intothe material passage. These rods serve as material engaging elements toknead the material coming into the crystallizer from the transfer unit11. The stator rods are positioned 45° apart. The rotor rods 119 arepositioned 15° apart. This staggering produces two effects, namely, notall of the stator and rotor rods come into mesh at the same time whichwould intermittently load the power drive, and there is less tendency ofthe material to fall through the material passage.

At the bottom of the material passage 118 a truncated conical gate 122is bolted to the rotor. By loosening the bolts (not shown) the gate maybe adjusted up and down with respect to the bottom of the stator wall,as indicated by arrows 123. This gate serves to control the flow fromthe bottom of the material passage 118, which in turn controls how highthe material builds up in that passage. The best results have beenobtained by having about the bottom one third of the passage filled withmaterial, but this may vary with particular apparatus, material, etc.

Below the material passage 118 is a chute 125 having an external wall126 thereabout. This wall has a discharge opening 127 for the release ofthe material. Cool air (e.g., 10° C.) is blown into the chamber definedby chute 125 and wall 126. This air is forced in by a blower 128 whichobtains the air from a suitable source 129. This cool air flows throughmaterial passage 118 countercurrent to the material flow and aids incooling the material. In some installations this air need only beambient air without any additional cooling.

Method and Operation

While each manufacturer of milk chocolate will have his own views as towhat exactly should be used as feed stock, what should be the degree ofcaramelization, etc., the following description is illustrative andthose familiar with the art of milk chocolate manufacture will be aware,from this description, of the modifications that they can make toachieve their desired result. Relative proportions of ingredients for achocolate crumb would be 51.71 kg. (114 pounds) of condensed sweet milk,1.59 kg. (3.5 pounds) of added sugar (e.g., cane sugar, etc.) and 6.17kg. (13.6 pounds) of dark chocolate liquor. If one were desiring to makewhite crumb, a representative feed stock would be 49.90 kg. (110 pounds)of condensed sweet milk and 1.81 kg. (4 pounds) of added sugar (cane,beet, etc.). Other flavoring ingredients, etc., may be employed in thefeed stock as desired.

The evaporator temperature (i.e., the temperature within jackets 19 and20) should be within the range of about 160° C. (320° F.) and about176.67° C. (350° F.). Like the other factors, the exact temperatureemployed is more of an art than a science, but an appropriatetemperature would be 168° C. (335° F.).

An ideal temperature for the condensed material exiting from theevaporator is 124.89° C. (255° F.) and the rate of feed of pump 34 isadjusted to give this result. To maintain this temperature and aid inextracting the condensed material (which is viscous and sticky) promptlyfrom the evaporator hood, the temperature within jacket 47 and heatingplate 45, is set at 129.44° C. (265° F.) and the stream temperature injacket 46 is 124.89° C. (255° F.). The temperature within steam jacket65 also would be 124.89° C. (255° F.). The operable range oftemperatures for the material exiting from the evaporator is 121.1° -126.67° C. (250° - 260° F.). Using another material temperature withinthis range, one would adjust the temperatures accordingly from thatgiven above for steam jackets 47 and 48. An important feature of theinvention is the ability to obtain the degree of caramelization and toadapt to particular formulas of feed stock, to meet the desires of theoperator. This is done by adjusting the temperatures and the rate offlow of the material.

The condensed material exiting from the transfer unit 11 is depositedupon a plate 135 at the top of the crystalizer, but below the top rods120. These top rods 120 are at each end of the plate. Thus, these rodsprevent a glob of material from suddenly descending into the materialpassage of the crystallizer. Instead, small quantities are extractedwith a shearing action as the moving rods 119 pass over the plate andbelow the top rods 120. In starting up, a small amount of crystallinematerial is placed on this shelf as "seed".

In the crystallizer, the material is pulled and worked much in the waythat one would work taffy. This may be referred to as a kneading action.As this is being done, heat is extracted and the material crystallizes.The rotor 86 is rotated at a peripheral speed of about 96 meters perminute (320 ft./min.). It is important to cool the material rapidly inthe crystallizer so as to obtain small sugar crystals. If the materialis not cooled rapidly, there is a tendency for the formation of largesugar crystals. Sugar "glass" may also be formed.

The material exiting from the crystallizer will be in particles havingsmall crystals, but with some agglomeration of the particles. Thematerial has only a small amount of fines. In terms of desirablecharacteristics from the standpoint of using the material for themanufacture of milk chocolate products, it is equal to or better thanthe material produced by conventional processes in use today.

The material exiting from the crystallizer (i.e., out opening 127) hasabout 4-6% moisture. If that material is to be used in the near futurein the further manufacture of chocolate products, it can be transferredto such other manufacturing operations without further processing.However, if it is to be stored for any length of time, the moisturecontent should be reduced to about 1%. Various forms of driers (e.g.,13) could be used for this purpose.

While the overall apparatus combination described herein is a highlydesirable unit by itself, this is not to say that the components neednecessarily be used together. For example, the evaporated materialexiting from the transfer unit 11 could be crystallized in an apparatusother than the unit 12 described herein. For example, it could bekneaded in a melangeur or other type of heavy mixing equipment presentlyin use and then dried in trays in vacuum ovens in accordance withconventional processes. Similarly, other forms of evaporators, e.g., amultiple tube type evaporator, could be employed to produce the pastewhich is then crystallized in the crystallizer 12 described herein.

The use of a descending path of flow in the crystallizer has anadvantage in the control of the degree of working of material as itcrystallizes. Speed of rotation of the rotor and the adjustment of gate122 are control factors in arriving at the desired result.

We claim:
 1. A process of preparing a crystalline product from a liquidfeed stock material comprising sugar, milk solids and a significantamount of moisture and utilizing a vertical evaporator having heatedwalls terminating at a top opening, said process comprising the stepsof:condensing said feed stock material to a readily crystallizablematerial by continuously introducing said feed stock material into thebottom of said evaporator and heating said material in said evaporatorsuch that upon reaching said top opening it has a temperature of betweenabout 121.1° C. and about 126.67° C. and a moisture content of betweenabout 4% and 6%; mechanically pushing said readily crystallizablematerial away from said top opening to a given location spaced from saidevaporator; and at said given location kneading said material removedfrom the evaporator while it crystallizes.
 2. A process as set forth inclaim 1 including the steps of maintaining the material in theevaporator at atmospheric pressure and heating said evaporator to atemperature of between about 160° C. and about 176.67° C.
 3. A processas set forth in claim 2 including the step of maintaining said condensedmaterial at a temperature of at least 121.1° C. from the time it isremoved from the evaporator to the time that the kneading commences. 4.A process as set forth in claim 3 including the steps of moving thecondensed material along a descending path while it is being kneaded,and cooling the condensed material as it is moved along said path.
 5. Aprocess as set forth in claim 4, wherein said kneading is preformed bypositioning a plurality of material engaging elements transversely insaid path, and moving some of said elements with respect to theremainder of said elements in a direction transverse to said path.
 6. Aprocess as set forth in claim 1, wherein chocolate is added to said feedstock material before introduction into said evaporator.
 7. A process ofpreparing a crystalline product from a liquid feed stock materialcomprising sugar, milk solids and a significant amount of moisturecomprising the steps of:continuously evaporating said feed stockmaterial to produce a condensed material having a temperature of between121.1° C and 126.67° C. and a moisture content of between about 4% andabout 6%; promptly moving said condensed material along a descendingpath; which said material is in said path kneading said material bypositioning a plurality of material engaging elements transversely insaid path, and moving some of said elements with respect to theremainder of said elements in a direction transverse to said path untilsaid material has crystallized; and cooling said material as it is beingkneaded.
 8. A process as set forth in claim 7, wherein chocolate isadded to said feed stock material.